Truing apparatus



Oct. 6, 1959 '0. E. HILL TRUING APPARATUS Filed Aug. 19, 1958 3 Sheets-Shet 1 IALQQ [H l a I62 )aa I INVENTOR O/vA E HILL A TTOENEY O 1 o. E. HILL 2,907,315

I mums APPARATUS Filed Aug. 19, 1958 9 3 Sheets-Sheet 2 0c 90 5 7? an qoa 5 A TTggA/EY Oct. 6, 1959 Filed Aug. 19, 1958 o. E. HILL TRUING APPARATUS 3 Sheets-Sheet 3 I73 6? M5 INVENTOR O/v E. H/L z.

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ATTORNEY I United States Patent TRUING APPARATUS Oiva E. Hill, West Boylston, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application August 19, 1958, Serial No. 756,003

14 Claims. (Cl. 125-11) The invention relates to grinding machines and more particularly to a grinding wheel truing apparatus.

One object of the invention is to provide a simple and thoroughly practical grinding wheel truing apparatus for truing a grinding wheel for a crank pin grinding machine. Another object of the invention is to provide a truing apparatus for truing a grinding wheel having a straight peripheral cylindrical surface with radii at opposite ends thereof. Another object is to provide a truing apparatus having a forming bar and a follower and synchronous driving connections between the follower and the truing tool for moving the truing tool in a predetermined path to true a radius, then a peripheral face and finally a second radius on a periphery of the wheel. A further object of the invention is to provide a truing apparatus in which the truing tool is moved continuously to true a plane side face, then a radius, then a peripheral cylindrical face, then a radius, and finally the opposite side face of a grinding wheel. Another object is to provide a truing apparatus in which the truing tool moves in a path to true the periphery of a crank pin grinding wheel in which the truing tool is stopped at either end of its stroke out of engagement with the grinding wheel. Other objects will be in part obvious or in part pointed out hereinafter.

One embodiment of the invention has been illustrated in the drawings in which:

Fig. l is a vertical sectional view through the improved grinding wheel truing apparatus;

Fig. 2 is a vertical sectional view, taken approximately on the line 22 of Fig. 1;

Fig. 3 is a combined hydraulic and electric diagram of the actuating mechanisms and the controls therefor;

Fig. 4 is a fragmentary plan view of the forming bar and associated parts as shown in Fig. 2; and

Fig. 5 is a diagrammatic view of the forming bar and the follower.

A hand wheel 26 is mounted on the upper end of the feed screw 20 to facilitate manual rotation of the feed screw 20 to facilitate a vertical adjustment of the slide 13; The lower end of the feed screw 20 is provided with a bevel gear 27 which meshes with a bevel gear 28 mounted on the right hand end of a rotatable shaft 29. The shaft 29 is rotatably journalled in a pair of spaced anti-friction bearings 39 and 31 (Fig. 1). A feed unit 32, to be hereinafter described is operatively connected to the left hand end of the shaft 29. This feeding mechanism is arranged to impart a feeding adjustment to the feed screw 20 and also to simultaneously impart an unwind and a wind motion thereto each time a feeding movement is imparted to the feed screw 20.

The vertically adjustable slide 13 supports a horizontally extending slide member 35 having horizontal parallel V-grooves 36 and 37 formed in the upper and lower sur faces thereof. The slide member 35 is arranged to support a horizontal movable slide 38 on an anti-friction bearing support comprising a pair of spaced rows of balls 39 and 40 which roll in spaced horizontally arranged V-grooves 41 and 42 on the slide 38.

In order to facilitate taking up lost motion between the slide parts, the V-groove 41 is preferably formed in a tapered gib 43 which is adjustably mounted on the slide 38. By manipulation of a screw 44 and a pair of opposed A grinding wheel truing apparatus has been illustrated in the drawings for truing the side faces, the peripheral face, and a radius on each corner of the grinding wheel. As illustrated in the drawings a grinding wheel 10 mounted on the conventional wheel spindle (not shown) is partially surrounded with a wheel guard 11. The wheel guard 11 serves as a support for the truing apparatus which includes a base 12 fixedly mounted on'the upper surface of the wheel guard 11. The base 12 supports a vertically adjustable slide 13 on a pair of spaced slide ways 14 and 15. 7

A feeding mechanism is provided for adjustingthe slide 13 vertically relative to the base 12 comprising a rotatable feed screw 20 which is journalled in spaced antifriction bearings 21 and 22 carried by the base 12. The vertically adjustable slide 13 is provided with a nut 23 (Fig. l) which meshes with or engages the feed screw nuts 45 and 46 (Fig. 2) the gib 43 may be adjusted longitudinally, as desired.

The slide 38 serves as a support for a vertically movable slide 50. The slide 50 is provided with a slide member 51 having spaced parallel V-grooves to guide a pair of spaced rows of balls 52 and 53 to form an anti-friction support for the vertically movable slide 50. A tapered gib 54 is carried by the horizontally movable slide 38. By manipulation of an adjusting screw 55 and a pair of spaced nuts 56 and 57, the gib 54 may be adjusted in a vertical direction to take-up any lost motion between the vertical slide 50 and the horizontal slide 38.

The lower end of the slide 50 supports a truing tool mechanism comprising a shaft 60 which is rotatably journalled in a pair of spaced anti-friction bearings 61 and 62. The bearings 61 and 62 are supported within a boss 63 formed integral with the slide 50. A truing tool head 64 is fixedly mounted on the left hand end of the shaft 60 (Fig. 1). The head 64 supports a slidably mounted sleeve 65 having a truing tool or diamond 66 mounted on its lower end. A feeding or adjusting mechanism is provided for the diamond 66 comprising a feed screw 67 which is rotatably supported by an end cap 68 fixedly mounted on the housing or boss 63. A manually operable adjust ing knob 69 is mounted on,the upper end of the feed screw 67. This knob is preferably provided with a grad? uated scale to facilitate adjusting a cutting point of the truing tool relative to the axis of rotation of the shaft 60. This adjustment serves to facilitate adjusting the radius generated on the corners of the grinding wheel.

' The upper end of the slide 50 is provided with an integral boss or housing which supports a rotatable shaft 76 in a pair of spaced anti-friction bearings 77 and 78. A follower 79 is pinned onto the shaft 76 so that it rotates therewith. The follower 79 is provided with a pair of spaced staggered projections 79a and 79b.

A driving mechanism is provided tosynchronize the rotary motion of the shaft 76 with the shaft 60. This driving mechanism comprises a sprocket 80 fixedly mounted on the shaft 76. The sprocket 80 is connected by a link chain 81 with a sprocket 82 fixedly mounted on the shaft 60. In order to facilitate setting'up thema-v chine and timing'the shaft 60 with the'shaftl76, apairf-of turnbuckles 83 and 84 are provided in thelinkchain "81 The staggered projections 79a and 79biof the follower 69 are arranged to engage and slide uponthe operative Patented Oct. 6, 1 959 surface of the template or forming bar 90. The forming bar 90 is fastened to the vertical slide 13 by a pair of screws 91 and 92. The screws 91 and 92 pass through elongated slots (not shown) formed in the slide 13 and are screw threaded into the forming bar 90 to facilitate a longitudinal adjustment thereof. The forming bar 90 is provided with a pair of opposed adjusting screws 93 and 94 (Fig. 2) by means of which the forming bar 90 may be adjustable in a horizontal longitudinal direction to facilitate positioning the forming bar in a predetermined relationship with the grinding wheel 10.

To facilitate truing opposite side faces of the grinding wheel adjacent to the periphery, truing the periphery, and truing a predetermined radius at each corner of the wheel, it is desirable to provide a continuous movement of the truing tool first in a direction normal to the grinding wheel axis to true the side face 10a of the grinding wheel 10, then to swing the truing tool 60 through an arc to true a radius 101) (Fig. 2). The truing tool is then traversed across the peripheral face 10c of the grinding wheel 10 after which the truing tool is swung through an arc to true a radius 10d, and then in a plane normal to the wheel axis to true a side face 102 adjacent to the periphery of the wheel 10. The shape of the forming bar or template 90 is arranged so that at the ends of the stroke of the truing tool, the truing tool is moved out of operative engagement with the grinding wheel 10.

The operative face of the forming bar 90 is provided with two offset spaced partial cylindrical surfaces 90a and 90b (Fig. 4) which are arranged so that the centers of curvature coincide with the axes of the radii to be generated on the opposite corners of the grinding wheel. The operative face of the template or forming bar 90 is also provided with staggered plane surfaces 900 and 9012'. The forming bar 90 is also provided with side faces 9011 and 90m which are arranged in planes normal to the axis of the grinding wheel 10 and serve to control the movement of the truing tool 66 while truing the plane side faces 10a and 10e of the grinding wheel (Fig. 2). The side faces 9% and 90m are located at a distance Y from the axes of the radii 10b and 10d, respectively which is equal to the distance X from the plane faces 90c and 90d from the axes of the radii 10b and 100 (Figs. 2 and so as to facilitate truing the radius and a tangent side face on the grinding wheel 10. The left hand end face of the forming bar 90 is provided with spaced bosses 90e, 90f and the right hand end face thereof provided with spaced bosses 90g and 90h. The bosses file-90 and 90g90h serve to move the truing tool 66 out of operative engagement with the side face a and 10e, respectively, of the grinding wheel 10 at the ends of its traversing stroke, and serve to maintain the truing tool out of operative engagement therewith during the grinding operation.

An actuating mechanism is provided for traversing the follower 79 so that its projections 79a and 7% follow the operative face of the forming bar 90 to generate a predetermined shape on the periphery of the grinding wheel. This mechanism comprises a slide block 96 which is rotatably supported on the shaft 76 and is arranged to slide within a slot 97 formed in a rock arm 98. The rock arm 98 is rotatably supported on a stud 99. A tension spring 100 is connected between a stud'101 fixedly mounted on slide 50 and a stud 102 fixedly mounted on the rock arm 98 (Fig. 1).

An actuating mechanism is provided for swinging the 'arm 98 comprising a cylinder 105 which contains a slidably mounted piston 106. The piston 106 is provided with rack teeth 107 on its upper surface which mesh with a gear segment 108 which is formed integral with the rock arm 98. A pair of adjustable stop screws 109 and 110 are provided to limit the movement of the piston 106 in either direction.

} When fluid under pressure is passed through a pipe 111 (Fig. 3) into alcylinder chamber 112, the piston 106 will, move toward the left thereby causing the rack teeth 107 to impart a clockwise rotary motion to the gear segment 108 and also to the rock arm 98 so as to swing the rock arm 98 successively through positions 98a, 98b, 98c, and 98d. During this movement, the slide block 96 causes a combined vertical and horizontal motion to be imparted to the slide 50 so as to true a predetermined shape on the operative face of the grinding wheel 10. During this movement fluid within a cylinder chamber 113 exhausts through a pipe 114.

A fluid pressure system is provided for supplying fluid under pressure comprising a motor driven fluid pump 120 which draws fluid through a pipe 121 from a reservoir 122 and forces fluid under pressure through a pipe 123. A relief valve 124 is connected to the pipe 123 to facilitate exhausting excess fluid under pressure from the pipe 123 so as to maintain a substantially uniform operating pressure within the system.

A solenoid-actuated control valve 125 is provided for controlling the admission to and exhaust of fluid from the cylinder chambers 112 and 113. The valve 125 is a piston type valve comprising slidably mounted valve member 126 having a plurality of spaced valve pistons formed integrally therewith to form a plurality of spaced valve chambers 127, 128, and 129. The valve member 126 is provided with a central pasage 130 which connects the valve chamber 127 with the valve chamber 129. A pair of balanced compression-springs 131 and 132 serve normally to maintain the valve member 126 in a central or neutral position. A pair of pull-type solenoids S1 and S2 are provided which when energized serve to shift the valve member 126 either toward the right or toward the left so as to control the flow of fluid.

A pipe 135 leading from the valve 125 is connected with a throttle valve 137 and a ball check valve 136 which are in turn connected with the pipe 111. Similarly a pipe 140 connected with the valve 125 is connected through a throttle valve 138 and a ball check valve 139 with the pipe 114.

A speed control valve 145 is provided to facilitate traversing the truing tool at one speed while truing the side faces and the radii on the corners of the wheel and automatically reducing the speed to a slower truing speed a as the truing tool 66 passes across the peripheral face of the grinding wheel 10. The valve 145 is a piston type valve comprising a slidably mounted valve member 146 the upper end of which rides upon a cam 147 which is fixedly mounted on the shaft 76. The valve member 146 is provided with a plurality of integral valve pistons which form a pair of spaced valve chambers 148 and 149. A compression spring 150 serves normally to hold the valve so as the upper end. 151 is maintained in operative engagement with the cam 147.

The pipe 111, as shown in Fig. 3 is connected with the valve chamber 148 which is in turn connected with the pipe 135. Similarly the pipe 114 is connected with the valve chamber 149 which connects with pipe 140.

When the solenoid S1 is energized, the valve member 126 moves toward the right (Fig. 3) so that fluid under pressure within the valve chamber 128 passes through the pipe 135. Fluid under pressure within-the pipe may pass through the ball check valve 136, through the throttle valve 137 and also through the chamber 148 in the valve 145 so that substantially an unrestricted flow of fluid is passed to the cylinder chamber 112 to start the piston 106 moving toward the left. During this movement fluid within the cylinder chamber 113 may exhaust through the pipe 114, through the throttle valve 138 and also through the valve chamber 149 in the valve 145, through the pipe into the valve chamber 127 and exhausts through the pipe 141 into the reservoir 122.

During movement of the piston 106 toward the left, the rock arm 98 is moved in a clockwise direction from the full line position (Fig. 2.) toward the position 93a. During this movement the projections 79a and 79b of the follower 79 ride 05 the bosses 90c and 90 so that the truing tool 66 is moved toward the right (Fig. 2) into operative engagement with the side face of a grinding wheel 10. Continued movement of the arm 98 causes the truing tool 66 to move upwardly to true a portion of the side face a after-which the projections 79a and 79b of the follower 79 ride on the cylindrical face 90a of the form 90 to true a radius 1011 on the grinding wheel 10. During truing of the radius 10b the cam 147 is rotated so that when the follower rides on the horizontal plane faces 90!: and 90d, the V 147a allows the release compression of the spring 150 to raise the valve member 146 upwardly so as to slow down the rate of movement of the piston 106 to slow down the traversing movement of the truing tool 66 while truing the peripheral face 100 of the grinding wheel 10. As the truing tool 66 completes the radius, the projections 79a and 79b ride onto the horizontal plane faces 90c and 90d so that a continued movement of the arm 98 imparts a longitudinal traversing movement to the slide 50 and the truing tool 66 to true the peripheral face 10c of the grinding wheel 10. As the truing tool 66 approaches the right hand end of the longitudinal traversing movement, the projections 79a and 79b of the follower 79 engage and slide along the partial cylindrical face 90b of the forming bar 90 so as to generate a radius 10d on the right hand corner of the grinding wheel. During this movement, the valve member 146 is depressed so as to speed up movement of the truing tool 66 while truing the radius 10 and the side face 10e. As the radius 10d is completed, the projections 79a and 79b of the follower 79 ride upon a vertical face 96m on the forming bar 90 so that the slide 50 together with the truing tool 66 moves in a vertical direction to true the side face 102 on the grinding wheel 10. After a predetermined truing on the side face ltle the projections 79a and 79b of the follower 79 ride upon the bosses or projections 90g and 90h which impart a longitudinal movement to the slide 50 to move the truing tool 66 into position 66d so that it is out of engagement with the grinding wheel 10.

- During the swinging movement of the rock arm 98 as produced by a longitudinal movement of the piston 106, a combined vertical movement of the slide 50 and a longitudinal movement of the slide 35 serves to cause the truing tool 66 to move through the several positions 66a, 66b, 66c, into position 66d as indicated in Fig. 2. As the rock arm 98 approaches position 98d, a limit switch LS2 is actuated to deenergize the solenoid S1 thereby releasing the compression of the spring 131 so that the valve member 126 returns to a central position.

I 7 When the solenoid S2 is energized, the valve member 126 is moved toward the left so that fluid under pressure entering the valve chamber 128 passes through the pipe 140 through the valve chamber 149 and also through the throttle valve 138 and the ball check valve 139 into the pipe 114 and the cylinder chamber 113 to start movement of the piston 106 toward the right. During movement of thepiston 106 toward the right, the slides 50 and 35 are moved similar to that previously described so that the truing tool 66 moves first vertically and toward the left from position 66d into engagement with the side face We of the grinding wheel 10 after which a continued vertical movement of the truing tool trues the side face lfie. The truing tool 66 then swings at a relatively fast speed in a counter-clockwise direction around the right hand corner of the grinding wheel to true the radius 10d afterwhich the truing tool 66 traverse at a slower speed in a horizontal direction across the operative face 160, said speeds being such that the tool 66 moves at a substantially uniform surface speed relative to the grinding wheel. At the end of the face 100, the truing tool 66 then swings in a counter-clockwise direction at a relatively fast speed'to true the radius 10b after which the truing'tool moves in a vertical downward direction to true a portionof the side face 10a of the grinding wheel 10 as the follower projections 79a and 79b ride down the face 901 When the projections 6 79a and 79b of the follower 79 ride upon the bosses We and 96 the truing tool 66 is moved in a longitudinal direction toward the left so that it is out of operative engagement with the grindingwheel 10.

When the truing tool is swung to a position for truing the cylindrical operative face of the grinding wheel 10, the cam 147 swings so that the V-shaped notch 147a is opposite the end 151 of the valve stem 146 at which time the released compression of the spring causes an upward movement of the valve stem 146 thereby cutting off the passage of fluid through the valve-145. When the valve 145 is in this position, the rate of traversing movement of the truing tool 66 while traversing across the cylindrical face 10c is controlled by the setting of the throttle valves 137 and 138.

During the swinging movement ofvthe rock arm 98 in either direction, the follower 79 being pinned to the shaft 76 imparts a rotary motion to the sprocket 80 which in turn transmits a corresponding motion through the ling chain 81 and the sprocket 82 so as to impart a corresponding movement to the truing tool 66.

A feeding mechanism is provided for automatically feeding the truing tool 66 toward the axis of the grinding wheel 10 before each traversing movement of the truing tool in either direction. This mechanism also includes means for imparting an unwind and a wind movement to the feed screw 20 at the time of each feeding movef ment. The shaft 29 is provided with a large gear which is keyed thereon. The hub of the gear 160 sup ports a bell crank lever 161 which is supported by the shaft 29.

A vertically extending arm162 of the bell crank lever 161 (Fig. 3) is provided with a yoked portion 163 which engages a stud 164 carried by a piston 165. The piston 165 is slidably mounted within a cylinder 166. The pis; ton 165 is normally held in a left hand end position by means of a compression spring 167. A shuttle type valve 168 is provided for controlling the admission to an exhaust of fluid from a cylinder chamber'169 through a port 170. The shuttle valve 168 is provided with a slidably mounted valve' piston 171. In the position, as shown in Fig. 3, when fluid under pressure is passed through a pipe 172 into a valve chamber 173, the pis ton 171 is moved downwardly (Fig. 3) to open the port so that fluid may pass into the cylinder chamber 169 to move the piston 165 toward the right thereby imparting a clockwise motion to the bell crank lever 161 so as to impart an unwind movement to the feed screw 20. When fluid is permitted to exhaust through the pipe 172, the released compression of the spring 167 serves to move the piston 165 toward the left thereby exhausting fluid from the cylinder chamber 169, through valve chamber 173 and out through the pipe 172 thereby moving the bell crank lever 161 in a counter-clockwise direction so as to impart a wind movement to the-feed screw 20.

Similarly when fluid under pressure is passed through the pipe 174 into the valve chamber 175, the valve member 171 is moved upward (Fig. 3) to open the port 170 so that fluid may pass into the cylinder chamber 169 to move the piston 165 toward the right thereby imparting a clockwise unwind movement to the feed screw 20. This takes place at theother end of the transversing stroke of the truing tool 66. When fluid may exhaust through the pipe 174, the released compression of the spring 167 serves to move the piston 165 toward the left thereby imparting a counterclockwise movement to the bell crank lever 161 so as to impart a wind movement to the feed screw 20. A

A horizontally extending arm of the bell crank lever 161 serves as a support for the feeding unit 32. The feed unit 32 includes a small gear 181 which is rotatably supported on a slidably mounted shaft 182. The small gear 181 meshes with the gear 160 and is arranged so that is free to rotate on the shaft 182 or may be clutched thereto by means of a clutch pin 183 which is 7 fixedly mounted on the shaft 182. As illustrated in Fig. 1 the clutch pin 183 is shown in operative engagement with a notch 184 formed in a hub portion of the gear 181.

The shaft 182 is provided with a plurality of V-grooves or notches 185, 186 and 187 which are arranged to be engaged by a spring-pressed ball 188 so as to hold the shaft in the desired axial position. If it is desired to declutch the gear 181 from the shaft 182, a knob 189 mounted on the end of the shaft 182 is moved toward the right (Fig. 1) until the spring pressed ball engages the groove 187 in which position the clutch pin 183 is moved out of engagement with the slot 184.

The feed unit 32 is provided with a pair of feed cylinders 190 and 192 which contain slidably mounted pistons 193 and 194 for imparting a feeding movement to the feed screw before each traversing movement of the truing tool 66. The pistons 193 and 194 are normally held in upper-most positions by a pair of compression springs 195 and 196. The pistons 193 and 194 are each provided with downwardly extending studs 197 and 198 which are arranged to engage adjustable stop screws 199 and 200 to limit the stroke of the pistons so as to control the extent of the feed movement.

The piston 193 is provided with a pawl 201 which is arranged to engage the teeth of a ratchet wheel 202 so that when the piston 193 is moved downwardly, the pawl 201 will ride idly over the teeth crank feed wheel 202. A serrated wheel 203 formed integral with the ratchet wheel 202 is engaged by a spring pressed plunger 204 to hold the ratchet wheel 202 against rotary motion of the ratchet Wheel202 during the idle stroke of the piston 193.

Similarly the piston 194 is provided with a pawl 2.05 which engages the teeth of the ratchet wheel 202 so that when the piston 194 is moved downwardly, the pawl 205 imparts a rotary motion to the ratchet wheel 202 which in turn serves to impart a feeding increment to the feed screw 20, through the gear 181 and the gear 160.

When fluid under pressure is passed through the pipe 174 it enters a cylinder chamber 206 formed in the upper end of the cylinder 190 to cause an idle downward stroke of the piston 193. When the pipe 174 is opened to the exhaust, as will be hereinafter described, the released compression of the spring 195 causes an upward movement of the piston 193 to impart a feeding movement to the ratchet wheel 202. This happens when the truing tool is about to start its traversing movement in one direction. Similarly when fluid under pressure is passed through the pipe 172, when the truing tool is at the other end of its stroke, it enters a cylinder chamber 207 formed in the upper end of the cylinder 192 thereby causing a downward movement to the piston 194 to impart a feeding movement to the ratchet wheel 202 which in turn transmits the feeding increment through the gear 181, the gear 160 so as to actuate the feed screw 20. When fluid in the pipe 172 is opened to exhaust, the released compression of the spring 196 causes an upward movement of the piston 194 during which movement the pawl 205 rides idly over the teeth of the ratchet wheel 202.

In order to facilitate a manual actuation of the feed screw 20, it is desirable to provide means for declutching the ratchet wheel 202 and the serrated wheel 203 from the shaft 182, thereby rendering the feed unit 32 inoperative. This is accomplished by providing the shaft 182 with a clutch pin 210 which is arranged to engage a slot 211 formed in the ratchet wheel 202. If it is desired to declutch the ratchet wheel 202 from the shaft 182, the knob 189 is moved so that the ball detent 188 engages the groove 186 formed inthe shaft 182. In this position the ratchet'wheel 202 and theserrated wheel 203 are free to rotate relative to the shaft 182. In this position of the parts a downward feeding adjustment of the slide 13 may be accomplished by manual manipulation of the hand wheel 26. t

A shuttle-type valve 215 is provided for controlling the admission to an exhaust of fluid from the unwindwind cylinder 166 and also to the feed cylinders 190 and 192 so that when the piston 106 starts moving in either direction a feeding increment will be imparted to the feed screw 20 and at the same time an unwind and a wind movement will be imparted thereto so as to take up the feed increment. This valve comprises a slidably mounted valve member 216 having a plurality of spaced valve pistons which form a pair of spaced valve chambers 217 and 218. A pair of throttle valves 219 and 220 are provided to control the admission to an exhaust of fluid from a pair of end chambers 221 and 222 so as to control the rate of shifting movement of the valve member 216. t

The operation of the improved truing apparatus will be readily apparent from the foregoing disclosure. A switch SW1 is closed to start the motor driven fluid pump to supply fluid under pressure to the system. When it is desired to start a truing cycle, a push button start switch FBI is actuated to close a circuit through the now closed contacts a of a limit switch LS1 to energize a relay switch CR1. Energizing relay switch CR1 closes the normally open contacts a and b of CR1. The closing of contacts b of relay switch CR1 sets up a holding circuit through the now closed contacts b of the limit switch LS2 to maintain the switch CR1 energized after the pushbutton switch FBI is released. The closing of contacts a of CR1 serves to energize the solenoid S1 thereby shifting the valve member 126 toward the right (Fig. 3). With the valve in this position fluid under pressure entering the valve chamber 128 passes through the valve and also through the ball check valve 136 and the throttle valve 137 into the cylinder chamber 112 to start the piston 106 moving toward the left. This movement of the piston 106 serves to start a swinging movement of the arm 98 in a clockwise direction to start movement of the truing tool 66. At the same time fluid under pressure in the pipe 135 passes through the throttle valve 220 into the end chamber 222 to start the valve member 216 moving toward left at a rate controlled by the throttle valve 219 and 220. Fluid under pressure in the pipe 135 also passes into the valve chamber 218 and through the pipe 174 into the cylinder chamber 206 to cause a downward movement of the piston 193. During the downward movement of the piston 193, the pawl 201 rides idly over the teeth of the ratchet wheel 202. Fluid under pressure passing through the pipe 174 enters the end chamber in the valve 168 and causes an upward movement (Fig. 3) of the valve piston 171. When the port 170 opens as the piston 171 reaches its uppermost position fluid under pressure passes into the cylinder chamber 169 to move the piston 165 toward the right (Fig. 3) thereby impartinga clockwise rotary motion to the bell crank lever 161. This movement of the bell crank lever serves to impart an unwind movement to the feed screw 20. The above takes place during the initial movement of the valve member 216 toward the left.

As soon as the valve member 216 of the shuttle valve 215 uncovers a port at the end of the pipe 141, the released compression of the spring 195 causes an upward movement of the piston during which movement the pawl 201 imparts a clockwise feeding movement to the ratchet wheel 202 thereby imparting a feeding increment to the feed screw 20. At the same time the released compression of the spring 167 shifts the piston 165 toward the left thereby imparting a counter-clockwise motion to the bell crank lever 162 so as to impart a wind movement to the feed screw 20. The above described feeding movement and the unwind-wind movement takes place instantaneously as soon as the piston 106 starts its traverse movement toward the left before the truing tool 66 starts truing the operative face of the grinding wheel 10. i

As soon as the arm 98 starts a swinging movement in 9, a clockwise direction to traverse the truing tool 66 across the operative face of the grinding wheel, the limit switch LS1 is released so that the normally open contacts a thereof open and the normally closed contacts b close. The relay switch CR1 remains energized since the holding circuit established at the start of the truing cycle through contacts b of CR1 and the normally closed contacts b of the limit switch LS2 maintains the solenoid S1 energized until the piston 106 reaches the left hand end of its stroke. As the arm 98 reaches the end of its clockwise swinging movement it actuates the limit switch LS2 opening the normally closed contacts b and closing the normally open contacts a, so as to break the holding circuit to deenergize CR1 and solenoid S1 thereby allowing the released compression of the spring 132 to return valve member 126 to a central or neutral position. The limit switch LS2 remains in this position until the start of the next truing cycle.

- When it is desired to start a truing cycle' in the opposite direction to move the truing tool from position 66d through the several positions into position 66, the pushbutton switch P132 is actuated which closes a circuit through the now closed contacts a of limit switch LS2 to energize a relay switch CR2 thereby closing the contacts a and b thereof. The closing of contacts a of relay switch CR2 sets up a holding circuit through the now closed contacts b of limit switch LS1 to maintain the relay switch CR2 energized during the entire truing stroke of the truing tool 66 from right to left. The closing of contacts b of relay switch CR2 serves to energize the solenoid S2 thereby shifting the valve member 126 toward the left so that fluid under pressure entering the valve chamber 128 passes through the pipe 140, through the valve 145 and also through the ball check valve 139 and the throttle valve 138 into the cylinder chamber 113 to start the piston 106 moving toward the right. Movement of the piston 106 toward the right serves to impart a counter-clockwise swinging movement to the arm 98. When fluid under pressure is passed through the pipe 140, it also passes through the throttle valve 219 into the end chamber 221 to shift the valve member 216 toward the right. Fluid under pressure in the pipe 140 also passes through the valve chamber 217, through the pipe 172 into the cylinder chamber 207 to cause a downward movement of the piston 192 thereby imparting a clockwise feeding movement to the ratchet wheel 202 to turn the .feed screw 20 thereby advancing the truing tool 66. 'At the same time fiuid under pressure passing through the pipe 172 enters the valve chamber 173 to cause a downward movement (Fig. 3) of the piston 171. When the piston 171 reaches its lowermost position fluid under pressure passes through the port 170 into the cylinder chamber 169 to move the piston 165 toward the right thereby/imparting a clockwise unwind movement to the bell crank lever 161 to impart an unwind movement to the feed screw 20.

During movement of the valve member 216 toward the right, as soon as the valve chamber 127 uncovers the port at the end of the pipe 141, the released compression of the. spring196 causes an upward movement of the piston 194 during which movement the pawl 205 rides idly over the teeth of the ratchet wheel 202. At the same time the released compression of the spring 167 exhausts fluid from the cylinder chamber 169, through the pipe 172 into the valve chamber 217 and exhausts through the pipe 141 into the reservoir 122. During this movement of the piston 165 toward the left," a counter-clockwise movement is imparted to the bell crank lever 161 thereby imparting a wind motion to the feed screw 20 so as to take-up the feed increment. a V, The above description of operation enables manual control. of the truing tool in either direction, when it is desired to make a single pass of the truing tool either toward the right or toward the left, by actuation of either the push-button switch PB1 or PB2. If however, it is desired to make two complete passes of the truing tool,

that is, toward the right and return toward the left, the switch SW2 may be closed after which the push-button switch PB1 may be actuated to initiate a truing cycle. The controls operate in the same manner as above described to traverse the truing tool 66 from the full line position into the broken line 66d. The switch SW2 being closed, a return stroke of the truing tool will be automatically initiated to impart a return stroke of the truing tool toward the left so that the truing tool moves from broken line position 66d into full line position 66 (Fig. 2).

If a continuous truing operation is desired, that is, a continuous traverse toward the right, then toward the left and so forth, the switch SW2 is closed after which a continuous truing cycle may be initiated by closing the switch SW3. With the switches SW2 and SW3 closed, the truing tool will traverse continuously, first toward the right, then toward the left and this movement will continue until the switch SW3 is manually opened to stop the continuous truing cycle. The continuous truing operation is particularly useful in the initial truing of a new grinding wheel.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore setforth, or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a grinding machine having a rotatable grinding wheel, a wheel guard partially surrounding said wheel, and a truing apparatus therefor including a base fixedly mounted on said guard, a vertically movable slide on said base, a feeding mechanism to feed said slide vertically relative to said base, a longitudinally movable slide on said vertical slide, a vertically movable carrier on said longitudinally movable slide, a truing tool holder rotatably mounted adjacent to the lower end of said carrier, a truing tool adjustably supported on said holder, a forming bar on said vertical slide, a follower rotatably supported adjacent to the upper end of said carrier,

means to move said follower across the operative face of the forming bar, synchronous driving connections between said follower and said truing tool holder to' impart a controlled movement to said truing tool.

2. In a grinding machine, as claimed in claim 1, having means including a motor to traverse said follower across the operative face of the forming bar, said forming bar being so shaped as to first impart a transverse movement to said carrier to true a plane side face on the grinding wheel, then a combined movement to the longitudinal slide and transverse movement to the carrier to true a radius on one corner of the grinding wheel, then a longitudinal movement to the longitudinal slide to true a peripheral face on the grinding wheel, then a combined movement to the longitudinal slide and transverse movement tothe carrier to true a radius on the other corner of the grinding wheel, and finally to impart a transverse movement to said carrierto true a plane side face on the other side of the grinding wheel.

3. A grinding machine having a rotatable grinding wheel, a wheel guard partially surrounding said wheel,

and a truing apparatus therefor including a base mounted on said guard, a transversely movable slide on said base,

11 a a latter'shaft, a forming bar on the transversely movable slide, yieldable means to maintain said follower in op-' erative engagement with said forming bar, and means. to move said follower relative to said forming bar so as to impart a corresponding movement to the truing tool.

4. A grinding machine, as claimed in claim 3, in which the synchronous driving connections include a sprocket on each of said shafts, a link chain connecting said sprockets, and adiustable connections in said linlr chain to. facilitate synchronizing the truing tool holder and the truing tool with said follower.

5. A grinding machine, as claimed in claim 3, in which a nut and screw feeding mechanism is provided between the truing tool and the holder, and a graduated adjusting means therefor to facilitate imparting a precise adjustment to the truing tool relative to the supporting shaft to vary the radius trued on the grinding wheel.

6. in a grinding machine, as claimed in claim 3, in combination with the parts and features therein specified, of a pivotally mounted yoked lever on said vertical slide which is operatively connected to move said follower, a motor included in said means to move said follower, and operative connections between said motor and said yoked lever to swing said lever thereby moving the follower across the operative face of the forming bar so as to true a predetermined shape on the grinding wheel.

7. In a grinding machine, as claimed in claim 3, in

combination with the parts and features therein specified, in which the forming bar is provided with a pair of spaced off'set cylindrical portions, the axes of saidport'ions being spaced to determine the axes of the radii to be trued on a grinding wheel, said barhaving off-set horizontal plane surfaces to control the truing tool during a peripheral truin operation, and a pair of spaced vertical plane side faces which are spaced apart to control truing of the plane side faces on opposite sides of the grinding wheel, said follower having off-set projections which ride upon the operative face of the forming bar successively to true a side face, a radius, a peripheral face, a radius, and a side face of the grinding wheel.

8. A grinding machine, as claimed in claim 3, in combination with the parts and features therein specified in which the the forming bar is shaped so as to cause first a vertical upward movement of the truing tool, then a swinging movemenh'then a horizontal movement, then a further swinging movement andfinally a vertical downward movement of the truing tool to true the predeterined shape on the periphery of the grinding wheel.

9. A grinding machine, as claimed in claim 3, in combination with the parts and features therein specified in which the forming bar is shaped so as to cause first a vertical upward movement of the carrier and truing tool to true a vertical plane side face of the grinding wheel, then a combined movement of the carrier and the longitudinal slide so as to swing said truing tool to true a radius, then a longitudinal movement of the longitudinal slide to traverse the truing tool longitudinally to true a peripheral face on the grinding wheel, then a combined movement of the carrier and the longitudinal slide so as to swing said truing tool to true a second radius, and finally a vertical downward movement of the transverse carrier and truing tool to true a vertical plane side face on the opposite side of the grinding wheel.

10. A grinding machine, as claimed in claim 3, in combination with parts and features therein specified, of a pivotally mounted yoked lever to move said follower relative to said template, a fluid motor operatively connected to actuate said lever so as to traverse the follower over the template thereby imparting a corresponding movement to the truing tool, a control valve to start and stop said motor, a normally closed speed control valve for said motor to facilitate moving the truing tool at one speed for truing portions of the operative face of the grinding wheel, and means including a cam actuated in "timed relation with the follower to actuate the speed r 7 l2 s t a control valve so as to slow down the control duringmovement of the truing tool while truing other portions of the operative face of the grinding wheel.

11. in a grinding machine, as claimed in claim 3, in which the, forming bar is provided with a pair of spaced ofif-set cylindrical portions, the axes of said portions being spaced to determine the axes of the radii to be trued on a grinding wheel, said bar having off-set horizontal plane surfaces to control the truing tool during a peripheral truing operation, a pair of spaced vertical plane side faces which are spaced apart to control truing of the plane side faces on opposite sides of the grinding wheel, and a pair of spaced projections on each of the plane side faces of the forming bar to move the truing tool out of engagement with the grinding wheel after the side faces of the grinding wheel have been trued to a predetermined extent.

12. A grinding machine having a rotatable grinding wheel, a wheel guard partially surrounding said wheel, and a truing apparatus therefor including a base mounted on said guard, a vertically movable slide on said base,

' a horizontally movable slide thereon, a vertically movable carrier on the longitudinally movable slide, a rotatable shaft adjacent to the lower end of said carrier, a truing tool holder on said shaft, a truing tool adjustably supported on said holder, a rotatable shaft adjacent to the upper end of said carrier, synchronous driving connections between said shafts, a follower having spaced offset projections which are fixedly mounted on the latter shaft, a forming bar on said vertically movable slide, yieldable means to maintain said follower projections in operative engagement with said forming bar, and means including a motor to move said follower relative to said forming bar so as to impart a corresponding movement to the truing tool.

13. A grinding machine having a rotatable grinding wheel, supporting means fixedly secured to said grinding machine, and a truing apparatus therefor attached to said supporting means including an articulated assembly for supporting and positioning a tool holder, at truing tool adjustably supported in said holder, an elongated forming bar mounted adjacent said assembly, a follower mounted upon said assembly and positioned in coordinated relation to said tool holder, yieldable means to maintain said follower in operative engagement with said forming bar, and means to move said follower relative to said forming bar so as to impart a corresponding movement to said truing tool, said forming bar having a pair of spaced off-set cylindrical portions, the axes of said portions being spaced to determine the axes of the radii to be trued on a'grinding wheel, off-set horizontal plane surfaces to control the truing tool during a peripheral truing operation, and a pair of spaced vertical plane side faces which are spaced apart to control truing of the plane side faces on opposite sides of the grinding wheel, said follower having off-set projections which ride upon the operative face of the forming bar successively to true a side face, a radius, a peripheral face, a radius,

. and a side face of the grinding wheel.

14. A grinding machine having a rotatable grinding wheel, supporting means fixedly secured to said grinding machine, and a truing apparatus therefor attached to said supporting means including an articulated assembly for supporting and positioning a tool holder, a truing tool adjustably supported in said holder, an elongated forming bar mounted adjacent said assembly, a follower mounted upon said assembly and positioned in coordinated re- 'lation to said tool holder, yieldable means to maintain said follower in operative engagement with said form'- ing bar, and means to move said follower relative to said forming bar so as to impart a corresponding movement to said truing too], said forming bar having a pair of spaced off-set cylindrical portions, the axes of said portions being spaced to determine the axes of the radii to be trued on a grinding wheel, off-set horizontal plane surfaces to control the truing tool during a peripheral truing operation, a pair of spaced vertical plane side faces which are spaced apart to control lining of the plane side faces on opposite sides of the grinding Wheel,

and a pair of spaced off-set projections on each of the 5 plane side faces of the forming bar to move the truing tool out of engagement with the grinding wheel after the side faces of the grinding wheel have been trued to a predetermined extent, said follower having off-set projeotions which ride upon the operative face of the forming bar successively to true a side face, a radius, a peripheral face, a radius, and a side face of the grinding wheel.

No references cited. 

